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2. sEdimENtary rocks
Rocks are constantly broken down into smaller
fragments and carried away by wind, water or ice

and deposited either on the sea bed or on land.
These smaller particles are called sediments. These
sediments are compressed, hardened and cemented
together to form layers of rocks called sedimentary
rocks or stratified rocks. Sandstone and limestone
are two important examples of sedimentary rocks.
Sedimentary rocks are made up of particles of various

sizes and deposited in horizontal layers one above Formation of Sedimentary Rocks
the other. These are softer than igneous rocks and
contain fossils of plants and animals between layers The word ‘Sedimentary’ originates from
or sediments. These rocks constitute 70% of all rocks a Latin word ‘Sedimenter’ which means
found on the earth’s surface. It is interesting to note settle down.
that all fossil fuels like coal and petroleum are found
in these rocks.

3. mEtamorphic rocks
Heat and pressure can change many things. They can
even change metamorphic rocks. Metamorphic comes
from Greek words meaning ‘change’ and ‘form’.

Metamorphic rocks form deep in the earth where high

temperature, great pressure, and chemical reactions
cause change from one type of rock to another type
Heat and Pressure of rock. The high temperature and pressure even

change the original properties like colour, texture, hardness and composition of minerals
available in it.
These rocks are formed of igneous
and sedimentary rocks when
subjected to intense heat and

pressure. For example, clay changes
into slate and limestone into marble.

The process of metamorphism
does not melt the rocks, instead it
transforms them into denser, more
compact rocks.

Examples : slate, marble, quartzite,
etc.
Changing of Metamorphic Rock

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